Presently available internal combustion engines require aftertreatment systems in many cases to meet stringent emissions requirements. In one example of an aftertreatment system, solid materials for ammonia (NH3) storage have been developed as a source of reductant in selective catalytic reduction (SCR). By dosing gaseous ammonia desorbed from solid storage media, the SCR system is capable of working at temperatures below the current limits of traditional urea-based SCR systems. Solid storage media systems for NH3 also operate without the negative aspects associated with urea-derived solid deposit problems in the exhaust system.
However, the use of a solid storage medium for production of gaseous NH3, provides new challenges related to the metering of gaseous NH3 to the exhaust system in order to achieve the desired operational outcomes.